Evolution (40 page)

Sometimes the climate shifts could be savage. Within a single year the amount of snowfall in an area could double, the average temperature fall by ten degrees. Faced with such chaotic oscillations, living things moved, or died.

Even the forests marched. Spruce proved a fast migrant, followed by pine, capable of marching at a kilometer every two years. The great chestnuts, massive trees with heavy seeds, could manage a pace of a hundred meters a year. Before the Ice Age the animals of the middle latitudes of the northern hemisphere had been a rich mixture of fleet grazers like deer and horses, giant herbivores like rhinos, and fast-running carnivores like lions and wolves. Now the animals were driven south in search of warmth. Populations of animals from different climatic zones were mixed up and forced to compete in fast-changing ecological arenas.

But some creatures began to adapt to the cold, to exploit the food supplies that still existed at the feet of the ice sheets. Many animals grew thick fur and layers of fat— large animals, like rhinos, and smaller animals, like foxes and horses and cats. Others began to take advantage of the huge temperature swings between the seasons. They migrated, moving north in the summer and south in the winter; the plains became a huge tidal wash of life, great mobile communities patiently stalked by predators.

There had been a catastrophe of mixing in the Americas. The two continents, north and south, had been separated since the shattering of Pangaea some one hundred and fifty million years ago. The fauna of South America had evolved in isolation, and was dominated by marsupial mammals and ungulates. There were marsupial “wolves” and saber-toothed “cats”; there were ungulate “camels” and trunked “elephants,” and giant ground sloths that could weigh three tons and stood six meters tall when they stood up to browse on palm leaves. There were still glyptodonts, not so dissimilar from the huge armored beast that had terrified Roamer, and the top predators were giant flightless birds, just as in archaic times. This exotic assemblage had been left alone to develop— though it was supplemented from time to time by waifs, brought by rafting or temporary bridges, like Roamer and her hapless companions, whose children had populated the South American jungles with monkeys.

But when the Panama land bridge was closed there was a massive migration from north to south of insectivores, rabbits, squirrels, mice, and later dogs, bears, weasels, and cats. The natives of South America failed to compete with these new arrivals. The extinctions took millions of years, but the empire of the marsupials was done.

For all the difficulty and dying, this time of fast and savage changes was, perversely, a time of opportunity. In the entire four-billion-year history of the Earth there had been few times more propitious for diversification and evolutionary innovation. Amid much extinction there was wild speciation.

And right at the center of this ecological cauldron were the children of Capo.

The next morning dawned brightly, with a washed-out blue sky. But the air was very dry and smelled oddly sharp, and the heat was soon stifling. The animals of the savannah seemed subdued. Even the birds were quiet; the carrion eaters clung to their tree roosts like ugly black fruit.

With their bare, sweating skin, the people were as well equipped for this hot, open dryness as any other species here. But they too began their day listlessly. They milled about their island of rock, picking at what was left of yesterday’s food.

This wasn’t a particularly rich area. The people didn’t discuss their plans— they never did, and anyhow they had no real plans— but it was obvious they shouldn’t stay here. Before long some of the men started to set off toward the water course to continue their walk to the south.

But the Brat’s condition had worsened overnight. The soles of his feet were cracked and oozing a watery pus, and when he tried to put his weight on them he cried out in pain. He wouldn’t be walking anywhere today.

Calm, Far’s grandmother, and most of the other women stayed close to the Brat. As for the men, the women just ignored their antics as they impatiently paced up and down the trail they had begun toward the south.

This conflict, all but wordless, over the day’s course was hurtful for them all. It was a genuine dilemma. The savannah was not like the bountiful, reliable forest of earlier times; you couldn’t just walk off in any random direction. Every day, in this sparse, changeable land, the people were faced with decisions about where to go to find food, water, what dangers to avoid. If they got it wrong, even once, the consequences were drastic. But the walkers had few children, and invested much effort in each one; you didn’t abandon one lightly.

At last the men gave up. Some of them returned to the rock to laze in the light of the high, hot sun. A handful of others set off under Brow’s leadership on the trail of an elephant herd, one of whose infants appeared to be limping. The rest of the men— and the women and older children— dispersed to the foraging sites they had explored yesterday.

The way these people were living— setting up a central home base, retrieving food, and sharing food and labor— was necessary. On the open plain the people had to work hard for food, and their slow-growing young extracted a high cost in care. They had to cooperate and share, one way or another. But there was no real planning. In many ways this was more like a wolf pack than any human community.

Far spent most of the morning in the same trampled thicket her mother had worked yesterday. The ground had already been thoroughly worked over, and to find new roots and fruit required much digging. Soon she was hot, dirty, and uncomfortable. She felt restless, confined, and her long legs, folded under her in the trampled dirt and debris, seemed to ache.

As noon approached, the desultory stillness of this strange, heavy day deepened. The savannah, open and free, beckoned Far, as it had done yesterday. As the emptiness in her belly diminished, the pressures of survival and familial duty were overcome by her longing to get
out
of here.

One spindly palm had survived the deinotheres’ attention, and it had a cluster of nuts at its top. A young man shimmied up the tree with a grace that came from his body’s deep-buried memory of earlier, greener times. Far watched his lithe torso working, and felt a peculiar ache at the base of her belly.

She came to a kind of decision. She dropped the last of the food, clambered out of the thicket, and just sprinted off to the west.

She felt a vast relief as her limbs worked, her lungs pumped, and she felt clean crisp dirt beneath her feet. For a time, as she ran without thinking, even the day’s heat seemed alleviated as the breeze of her passing cooled her skin.

Then there was a deep, menacing rumble that echoed across the sky. She pulled up, crouched, and peered around fearfully.

The bright sunlight dimmed. Thick black clouds were pouring across the sky from the east. She was startled by a flash of purplish light that lit up the clouds from within. Almost immediately there was a shattering crash and a deeper, drawn-out rumble that seemed to roll around the sky.

Looking back at the rocky outcrop, which suddenly seemed very far away, she saw the people running, gathering up their infants. Her heart hammering, Far straightened up and began to head back.

But now rain lashed down from the blackening sky. The drops were heavy enough to sting her bare skin and unprotected scalp, and they dug small craters in the dirt. The ground rapidly turned to sticky mud that clung to her feet, slowing her down.

Light flashed again, this time a great river of it that briefly connected sky to ground. Dazzled, she stumbled and fell in the mud. Shattering noise pealed around her, as if the world were falling apart.

She saw that the tall palm at the center of the trampled clearing had been split in two, and it was blazing, the flames licking at the fronds that dangled forlornly from its tip. The fire quickly spread through the rest of the smashed thicket— and then the dry grass on the plain beyond began to catch.

A pall of gray-black smoke began to rise up before her. She got to her feet and tried to continue. But, despite the continuing rain, the fire spread quickly. The season had been exceptionally dry, and the savannah was littered with yellowed grass, dried shrubs, fallen trees ripe for burning. Somewhere an elephant trumpeted. Far glimpsed spindly forms fleeing through the murk: giraffes, perhaps.

The hominids were safe, though. The flames would lap harmlessly around their rocky outcrop. Though they would all suffer from the smoke and heat, nobody would die because of this. And if Far could reach the outcrop, she, too, would be safe. But she was still hundreds of meters away, and the screen of smoke and flame cut her off. The flames were leaping hungrily over the long, dry grass, each blade of which burned in an eye blink. The air turned smoky, making her cough. Bits of burning vegetation drifted through the air, blackened, still glowing. When they fell on her skin they stung.

She did the only thing she could do. She turned and ran: ran to the west, away from the fire, away from her family.

She didn’t stop running until she came to a dense thicket of forest. Facing a blank, green wall, she hesitated for one heartbeat. Other dangers lurked here, but this place was surely invulnerable to the fire. She plunged inside.

Crouched close to the root of a tree fern, surrounded by damp clinging fronds, she peered out at the savannah. The fire still swept voraciously through the long grass, and smoke billowed, seeping into the dense forest. But this forest clump was indeed too dense and moist to be under threat. And the fire was quickly consuming its fuel; the rain was starting to douse the flames.

Soon she would be able to get out of here. She squatted down to wait it out.

A scuttling movement close to her foot drew her attention. At the base of the tree fern’s textured root a scorpion moved with metallic precision toward her foot. Without hesitation, but taking care to avoid the sting, she slammed the heel of her hand down on the scorpion. Carefully she picked up the scorpion between two fingers, and lifted it to her mouth.

Something rammed into her back. She was thrown forward onto her belly, with a mass on her back, hot, heavy, muscular. She was surrounded by screeching and hooting, and fists pounded at her back and head.

Winded, summoning up her strength, she rolled over.

A slim figure capered over her. It was not much more than half her height, with a skinny body covered with brown-black fur, long arms, an apelike head stuck over a narrow, conical chest, and a thin pink penis sticking out below its belly. Its fur was wet from the rain, and it stank, the smell musty and strong. And yet it— he— stood upright over her, like one of her own kind, like no ape.

This was a pithecine: an ape-man, a chimp-man, a representative of the first hominids of all, Far’s remote cousin. And there were more of them in the jumbled branches above her, climbing down like shadows.

She turned to get up. But something slammed against her head, and she fell into blackness.

When she came to she was flat on her back. Her chest, legs, and buttocks ached.

Pithecines were all around her.

Some of them had clambered into pod mahogany trees in search of fruit. Others were digging in the ground, pulling out corkwood roots. They were active, foraging bipeds, working wordlessly. But, unlike her, they were short, hairy, their skin slack like chimps’.

Somebody was screaming. Far turned her head to see.

A pithecine was crouched in the dirt. It— she— was straining, her face contorted, her slack breasts heavy with milk. Far, blearily, saw a small solid mass emerge from her rump: mucus-covered, hairy, it was the head of a baby. This pithecine woman was giving birth.

Other females surrounded her, sisters, cousins, and her mother. Chattering and hooting softly, they reached between the new mother’s legs. Gently they fumbled with the baby as, moistly, it was pushed out of the birth canal.

The new mother faced problems no earlier primate had endured, for the baby was being born facing away from her. Leaf, a female of Capo’s time, would have been able to see her baby’s face as it emerged, and would have been able to reach down between her legs to guide her baby’s head and body out of her birth canal. If this pithecine were to try that she would bend the baby’s neck backward and risk injuring its spinal cord, nerves, and muscles. She could not cope alone, as Leaf could have— but she did not have to.

When the baby’s hands were free, it grabbed at its mother’s fur and began to pull. Even now it was strong enough to aid in its own delivery.

It was all a consequence of bipedalism. A quadruped supported its abdominal organs with connective tissue hung from its backbone. The pelvis was just a connecting element that translated the pressure on the backbone down and outward to the hips and legs. But if you decided to walk upright your pelvis had to support the weight of your abdominal organs— and the weight of a growing embryo inside you. The pelvises of the upright pithecines had quickly adapted, becoming like a human’s basin-shaped supporting structure. The central opening for the birth canal changed too, becoming larger side to side than front to back, an oval shape to match a baby’s skull.

This pithecine mother’s birth canal was narrower in comparison to her baby’s head than any previous primate’s. Her baby had entered the canal facing its mother’s side, to let its head through. But then it had to turn so its shoulders lined up with the canal’s widest dimension. Sometimes the baby would finish up in the easiest position, facing its mother, but more often than not it would turn away from her.

In the future, as hominid skulls increased in size to accommodate larger brains, still more elaborate redesigns of the birth passageways would be required, so that Joan Useb’s baby would have to twist and turn in a complicated fashion as it headed for the light. But even in these deep times, the first bipedal mothers already needed midwives— and a new kind of social bond had been forged among the pithecines.

At last the baby emerged fully, falling to the leaf-strewn ground with a plop, its small fists closing. The mother fell to the ground with a gasp of relief. One older pithecine picked up the child, cleared plugs of mucus from its mouth and nose, and blew into its nostrils. At the hairy little scrap’s first wail, the midwife peremptorily thrust the baby at its mother and loped away.